1. Field of the Invention
The present invention relates to a pressure sensitive adhesive tape or sheet and more specifically, to a pressure sensitive adhesive tape or sheet containing a plurality of artificial filament yarns buried in the tape and arranged in parallel to the longitudinal direction of the tape and, having a high tensile strength in the longitudinal direction of the tape.
2. Description of the Prior Art
Conventional strong pressure sensitive tapes with buried-in artificial filament yarns are known, for example, in accordance with the description in the Japanese official bulletin "Published unexamined patent application, Showa 29-2989." This adhesive tape is produced by providing, in advance, an adhesive single-coated tape which has the pressure sensitive adhesive layer on one side of the supporting sheet consisting of resin, paper, etc. A plurality of glass filament yarn fibers are disposed on the adhesive layer parallel to the longitudinal direction of said sheet, with another adhesive layer being applied thereto. In this structure, said filament yarns are thoroughly buried in said pressure sensitive adhesive layer, but they have no contact with the supporting sheet. Such an adhesive tape has the defects that lifting or puckering occurs when unwinding the rolled adhesive tape because the filament yarns are buried in the adhesive layer provided on the supporting sheet and thus, when the rolled adhesive tape is peeled at the end, only the supporting sheet peels off. In addition, the tape itself has the defect that, depending on the types of the applied adhesives, it is liable to age and change its properties in the course of time and, as a result, the filament yarns arranged in parallel along the longitudinal direction of the tape, at the point of manufacture, tend to snake while they are stored on the shelf, and thus the commercial value of the tape is extraordinarily lowered. Accordingly the conventional adhesive tape has serious defects in its manufacturing processes and also in its structure.
Accordingly an object of the present invention is to provide a pressure sensitive adhesive tape, in which filament yarns are arranged in parallel to the longitudinal direction on the supporting sheet, which eliminates lifting and puckering when the rolled tape is unwound and avoids peeling-off of only the supporting sheet at the end of the tape.
Another object of the present invention is to provide a pressure sensitive adhesive tape in which filament yarns arranged in parallel to the longitudinal direction of the supporting sheet at the point of manufacture cause no snaking due to aging and changing its properties in the course of time while it is being stored on shelf.
A further object of the present invention is to provide a pressure sensitive adhesive tape which can be produced by a simple manufacturing process.